We investigate a method for determining the elemental composition of biological samples that uses prompt gamma rays induced by 14,7-MeV neutrons. Alpha particles are produced simultaneously with the neutrons, which exit opposite the alpha detector through the vacuum chamber wall The sample under investigation is irradiated and emits gamma radiations in a spectral energy distribution characteristic of the material Barium-fluoride (BaF2) and high-purity germanium (HPGe) gamma detectors view the sample and record the spectrum of gamma radiation.

A simple method for the determination of the total width of the 9.17 MeV level in 14N is described. The method is based on the use of a resonant detector which contains nitrogen in its active volume. With the help of the resonant detector the ratio of Γγ0/ΓT was found to be 0.052 ± 0.004. This result together with the data from a conventional resonant absorption experiment yields for the total width of the level a value of 122±8 eV.

We describe an ''associated particle'' method for producing three-dimensional images. Based on the t(d,n)/sup 4/He reaction, the method requires access to only one side of the object being imaged. A major advantage of the technique is that it is possible to produce separate images for individual chemical elements in the material under observation. Studies were performed to select alpha-particle and gamma-ray detectors, to optimize experimental parameters, and to evaluate the effect of intervening materials between the neutron sources and the object under observation. 9 refs., 22 figs., 5 tabs.

A search for the rare decay ${K}^{+}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{e}^{+}{e}^{\ensuremath{-}}$ has been carried out at the Lawrence Berkeley Laboratory using a sparkostrictive wire-chamber spectrometer. Analysis programs identified events with three tracks or with two tracks of which one was an electron and the other a positron. Analysis of the three-track events yields a branching ratio $\frac{\ensuremath{\Gamma}({K}^{+}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{e}^{+}{e}^{\ensuremath{-}})}{\ensuremath{\Gamma}({K}^{+}\ensuremath{\rightarrow}\mathrm{all})}<1.7\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6}$ (90% confidence). The two-track events, analyzed by searching for sparks on a possible pion track, yield a limit of $\frac{\ensuremath{\Gamma}({K}^{+}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{e}^{+}{e}^{\ensuremath{-}})}{\ensuremath{\Gamma}({K}^{+}\ensuremath{\rightarrow}\mathrm{all})}<2.7\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}7}$ (90% confidence). The latter value implies that the coupling constant for a vector neutral current must be about three orders of magnitude smaller than the coupling constant for the charged vector current.

We describe a compact, light-weight, image-intensified scintillator detector with video output developed for low-intensity (<1010 particles/cm2 s) beam monitoring.

The development of a sparkostrictive wire-chamber spectrometer is described. The spectrometer consists of 9 chambers ranging in active width-times-height from 91 cm × 81 cm to 152 cm × 91 cm. The chambers are positioned between the 152-cm-diameter pole faces of the Lawrence Berkeley Laboratory M5 magnet, which has a 120-cm gap and a 6-kG field in this application. The grid wires are spaced 1 mm apart and on most chambers are oriented with wires running vertically and at ±30° angles to the vertical to provide three redundant coordinates per track. The root-mean-square spatial resolution is typically 1.6 mm. The chambers, while capable of one-track efficiencies of virtually 100% and three-track efficiencies averaging better than 98% per track, are extremely delicate and require constant attention. The various steps taken to achieve high efficiencies are analyzed, and the performance during a recent Ke4+−Kπee+ experiment involving more than 1.6 × 106 triggers is evaluated.